Cephem compounds

Abstract

The invention relates to novel compounds of high antimicrobial activity of the formula: ##STR1## wherein R 1 is amino or protected amino, R 2 is carboxy(lower)alkyl or protected carboxy(lower)alkyl, and R 3 is carboxy or protected carboxy, and a pharmaceutically acceptable salt thereof.

What we claim is: 
     
       1. A compound of the formula: ##STR6## wherein R 1  is amino or protected amino, R 2  is carboxy(lower)alkyl or protected carboxy(lower)alkyl, and   R 3  is carboxy or protected carboxy, and a pharmaceutically acceptable salt thereof.     
     
     
       2. A compound of claim 1, which is 7-[2-carboxymethoxyimino-2-(5-amino-1,2,4-thiadiazol-3-yl)acetamido]-3-azidomethyl-3-cephem-4-carboxylic acid (syn isomer).   
     
     
       3. An antibacterial composition comprising an effective amount of a compound of claim 1 in association with a pharmaceutically acceptable substantially non-toxic carrier or excipient.